【润学】计算机网络八股文英文版(1)

  润学不知道从什么时候开始流行起来了。应润尽润，不管能不能成功，先做好准备。首先从网络开始，分 Basic、Intermediate、Advanced 三节，今天更新 Basic。

What is the network?

The computer network is a system of peripherals or computers interconnected with each other and has a standard communication channel established between them to exchange different types of information and data.

什么是网络？

计算机网络是外围设备或计算机相互连接的系统，它们之间建立了标准的通信通道，用于交换不同类型的信息和数据。

Basic Networking Interview Questions

Question 1. How are Network types classified?

Network types can be classified and divided based on the area of distribution of the network. The below diagram would help to understand the same:

1. 网络类型如何分类？

网络类型可以根据网络的分布区域进行分类和划分。下图将有助于理解相同的内容：

Question 2. Explain different types of networks.

Below are few types of networks:

• PAN (Personal Area Network): Let devices connect and communicate over the range of a person. E.g. connecting Bluetooth devices.
• LAN (Local Area Network): It is a privately owned network that operates within and nearby a single building like a home, office, or factory.
• MAN (Metropolitan Area Network): It connects and covers the whole city. E.g. TV Cable connection over the city.
• WAN (Wide Area Network): It spans a large geographical area, often a country or continent. The Internet is the largest WAN.
• GAN (Global Area Network): It is also known as the Internet which connects the globe using satellites. The Internet is also called the Network of WANs.

2. 解释不同类型的网络。

以下是几种类型的网络：

• PAN（个人局域网）：让设备在一个人的范围内进行连接和通信。例如连接蓝牙设备。
• LAN（局域网）：它是一个私有网络，在家庭、办公室或工厂等单一建筑物内和附近运行
• MAN（城域网）：它连接并覆盖了整个城市。例如，城市上的电视电缆连接
• WAN（广域网）：它跨越一个很大的地理区域，通常是一个国家或大陆。互联网是最大的广域网
• GAN（全球区域网络）：它也被称为使用卫星连接全球的互联网。互联网也称为广域网网络。

Question 3. Explain LAN (Local Area Network)

LANs are widely used to connect computers/laptops and consumer electronics which enables them to share resources (e.g., printers, fax machines) and exchange information. When LANs are used by companies or organizations, they are called enterprise networks. There are two different types of LAN networks i.e. wireless LAN (no wires involved achieved using Wi-Fi) and wired LAN (achieved using LAN cable). Wireless LANs are very popular these days for places where installing wire is difficult. The below diagrams explain both wireless and wired LAN.

3.解释LAN（局域网）

LAN 广泛用于连接计算机/笔记本电脑和消费电子产品，使它们能够共享资源（例如，打印机、传真机）和交换信息。当公司或组织使用 LAN 时，它们被称为企业网络。有两种不同类型的 LAN 网络，即无线 LAN（使用 Wi-Fi 实现不涉及电线）和有线 LAN（使用 LAN 电缆实现）。如今，无线 LAN 在难以安装电线的地方非常流行。下图解释了无线和有线 LAN。

Question 4. Tell me something about VPN (Virtual Private Network)

VPN or the Virtual Private Network is a private WAN (Wide Area Network) built on the internet. It allows the creation of a secured tunnel (protected network) between different networks using the internet (public network). By using the VPN, a client can connect to the organization’s network remotely. The below diagram shows an organizational WAN network over Australia created using VPN:

4.告诉我一些关于VPN（虚拟专用网络）的事情

VPN 或虚拟专用网络是建立在互联网上的专用 WAN（广域网）。它允许使用互联网（公共网络）在不同网络之间创建安全隧道（受保护网络）。通过使用 VPN，客户端可以远程连接到组织的网络。下图显示了使用 VPN 在澳大利亚创建的组织 WAN 网络：

Question 5. What are the advantages of using a VPN?

Below are few advantages of using VPN:

• VPN is used to connect offices in different geographical locations remotely and is cheaper when compared to WAN connections.
• VPN is used for secure transactions and confidential data transfer between multiple offices located in different geographical locations.
• VPN keeps an organization’s information secured against any potential threats or intrusions by using virtualization.
• VPN encrypts the internet traffic and disguises the online identity.

5. 使用 VPN 有什么好处？

以下是使用 VPN 的几个优点：

• VPN 用于远程连接不同地理位置的办公室，与 WAN 连接相比更便宜。
• VPN 用于在位于不同地理位置的多个办公室之间进行安全交易和机密数据传输。
• VPN 通过使用虚拟化来保护组织的信息免受任何潜在威胁或入侵。
• VPN 加密互联网流量并伪装在线身份。

Question 6. What are the different types of VPN?

Few types of VPN are:

• Access VPN: Access VPN is used to provide connectivity to remote mobile users and telecommuters. It serves as an alternative to dial-up connections or ISDN (Integrated Services Digital Network) connections. It is a low-cost solution and provides a wide range of connectivity.
• Site-to-Site VPN: A Site-to-Site or Router-to-Router VPN is commonly used in large companies having branches in different locations to connect the network of one office to another in different locations. There are 2 sub-categories as mentioned below:
• Intranet VPN: Intranet VPN is useful for connecting remote offices in different geographical locations using shared infrastructure (internet connectivity and servers) with the same accessibility policies as a private WAN (wide area network).
• Extranet VPN: Extranet VPN uses shared infrastructure over an intranet, suppliers, customers, partners, and other entities and connects them using dedicated connections.

6. 有哪些不同类型的 VPN？

几种类型的VPN是：

• Access VPN： Access VPN 用于为远程移动用户和远程办公人员提供连接。它用作拨号连接或 ISDN（综合服务数字网络）连接的替代方案。它是一种低成本的解决方案，可提供广泛的连接性。
• **站点到站点 VPN：**站点到站点或路由器到路由器 VPN 通常用于在不同位置设有分支机构的大公司，以将一个办公室的网络连接到不同位置的另一个办公室。有2个子类别，如下所述：
• Intranet VPN： Intranet VPN 对于使用共享基础设施（互联网连接和服务器）连接不同地理位置的远程办公室非常有用，其可访问性策略与专用 WAN（广域网）相同。
• Extranet VPN： Extranet VPN 在 Intranet、供应商、客户、合作伙伴和其他实体上使用共享基础架构，并使用专用连接将它们连接起来。

Question 7. What are nodes and links?

Node: Any communicating device in a network is called a Node. Node is the point of intersection in a network. It can send/receive data and information within a network. Examples of the node can be computers, laptops, printers, servers, modems, etc.

Link: A link or edge refers to the connectivity between two nodes in the network. It includes the type of connectivity (wired or wireless) between the nodes and protocols used for one node to be able to communicate with the other.

7. 什么是节点和链接？

**节点：**网络中的任何通信设备都称为节点。节点是网络中的交点。它可以在网络内发送/接收数据和信息。节点的示例可以是计算机、笔记本电脑、打印机、服务器、调制解调器等。

**链接：**链接或边是指网络中两个节点之间的连通性。它包括节点之间的连接类型（有线或无线）以及用于一个节点能够与另一个节点通信的协议。

Question 8. What is the network topology?

Network topology is a physical layout of the network, connecting the different nodes using the links. It depicts the connectivity between the computers, devices, cables, etc.

8、什么是网络拓扑？

网络拓扑是网络的物理布局，使用链路连接不同的节点。它描述了计算机、设备、电缆等之间的连接。

Questions 9. Define different types of network topology

The different types of network topology are given below:

Question 9.定义不同类型的网络拓扑

不同类型的网络拓扑如下所示：

Bus Topology:

• All the nodes are connected using the central link known as the bus.
• It is useful to connect a smaller number of devices.
• If the main cable gets damaged, it will damage the whole network.

总线拓扑：

• 所有节点都使用称为总线的中央链路连接。
• 连接较少数量的设备很有用。
• 如果主电缆损坏，将损坏整个网络。

Star Topology:

• All the nodes are connected to one single node known as the central node.
• It is more robust.
• If the central node fails the complete network is damaged.
• Easy to troubleshoot.
• Mainly used in home and office networks.

星型拓扑：

• 所有节点都连接到一个称为中心节点的单个节点。
• 它更健壮。
• 如果中央节点发生故障，整个网络就会损坏。
• 易于故障排除。
• 主要用于家庭和办公网络。

Ring Topology:

• Each node is connected to exactly two nodes forming a ring structure
• If one of the nodes are damaged, it will damage the whole network
• It is used very rarely as it is expensive and hard to install and manage

环形拓扑：

• 每个节点恰好连接到两个节点，形成一个环形结构
• 如果其中一个节点损坏，将损坏整个网络
• 它很少使用，因为它昂贵且难以安装和管理

Mesh Topology:

• Each node is connected to one or many nodes.
• It is robust as failure in one link only disconnects that node.
• It is rarely used and installation and management are difficult.

网状拓扑：

• 每个节点都连接到一个或多个节点。
• 它是健壮的，因为一个链接中的故障只会断开该节点。
• 很少使用，安装管理困难。

Tree Topology:

• A combination of star and bus topology also know as an extended bus topology.
• All the smaller star networks are connected to a single bus.
• If the main bus fails, the whole network is damaged.

树拓扑：

• 星形和总线拓扑的组合也称为扩展总线拓扑。
• 所有较小的星形网络都连接到一条总线。
• 如果主总线出现故障，整个网络就会受损。

Hybrid:

• It is a combination of different topologies to form a new topology.
• It helps to ignore the drawback of a particular topology and helps to pick the strengths from other.

混合：

• 它是不同拓扑的组合，形成一个新的拓扑。
• 它有助于忽略特定拓扑的缺点，并有助于从其他拓扑中挑选优势。

Question 10. What is an IPv4 address? What are the different classes of IPv4?

An IP address is a 32-bit dynamic address of a node in the network. An IPv4 address has 4 octets of 8-bit each with each number with a value up to 255.

IPv4 classes are differentiated based on the number of hosts it supports on the network. There are five types of IPv4 classes and are based on the first octet of IP addresses which are classified as Class A, B, C, D, or E.

• Class A from 0.0.0.0 to 127.255.255.255, used for large network
• Class B from 128.0.0.0 to 191.255.255.255, used for medium size network
• Class C from 192.0.0.0 to 223.255.255.255, used for local area network
• Class D from 224.0.0.0 to 239.255.255.255, reserved for multicasting
• Class E from 0.0.0.0 to 127.255.255.255, study and R&D

10. 什么是 IPv4 地址？IPv4有哪些不同的类别？

IP 地址是网络中节点的 32 位动态地址。IPv4 地址有 4 个 8 位八位字节，每个数字的值最大为 255。

IPv4 类根据它在网络上支持的主机数量来区分。IPv4 有五种类型，基于 IP 地址的第一个八位组，分为 A、B、C、D 或 E 类。

IPv4 Class	IPv4 Start Address	IPv4 End Address	Usage
A	0.0.0.0	127.255.255.255	用于大型网络
B	128.0.0.0	191.255.255.255	用于中型网络
C	192.0.0.0	223.255.255.255	用于局域网
D	224.0.0.0	239.255.255.255	保留用于多播
E	240.0.0.0	255.255.255.254	研究与研发

Question 11. What are Private and Special IP addresses?

Private Address: For each class, there are specific IPs that are reserved specifically for private use only. This IP address cannot be used for devices on the Internet as they are non-routable.

Special Address: IP Range from 127.0.0.1 to 127.255.255.255 are network testing addresses also known as loopback addresses are the special IP address.

11. 什么是专用 IP 地址和特殊 IP 地址？

**私有地址：**对于每个类，都有专门为私人使用而保留的特定 IP。此 IP 地址不能用于 Internet 上的设备，因为它们是不可路由的。

**特殊地址：**从 127.0.0.1 到 127.255.255.255 的 IP 范围是网络测试地址，也称为环回地址，是特殊 IP 地址。

IPv4 Class	Private IPv4 Start Address	Private IPv4 End Address
A	10.0.0.0	10.255.255.255
B	172.16.0.0	172.31.255.255
B	192.168.0.0	192.168.255.255

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